In wireless communication, a base station needs to send system information to a user equipment (UE). The UE can obtain related network configuration information only after receiving the system information, so as to access the base station and communicate with the base station.
The system information sent by the base station to the UE includes system information such as a system information block (SIB) and/or a master information block (MIB). The system information is information broadcast by the base station to all UEs within a coverage area. The base station further sends, to the UE, information including paging information, a random access response (RAR) message, a contention resolution message, and the like. A feature of the information is: Although the information is broadcast by the base station to the UE, the base station may send the same information to a group of UEs, and the base station may send different information to multiple groups of UEs. In addition, the base station further needs to send control information for scheduling system information, control information for scheduling an RAR message, control information for scheduling a paging message, or control information for scheduling a contention resolution message to the UE.
Currently, with the development of machine-to-machine (M2M) technologies, there are multiple UEs of low complexity or low costs in a network. The UE of low complexity or low costs supports (radio frequency and/or baseband) bandwidth that is less than maximum carrier bandwidth stipulated in the system or is not greater than specific frequency bandwidth. When the UE of low complexity or low costs is served on a carrier whose bandwidth is greater than the bandwidth supported by the UE of low complexity or low costs, the UE can receive or send data on only one sub-band resource of the carrier at the same moment. If the base station transmits information such as system information, an RAR message, a paging message, or a contention resolution message (or control information for scheduling information such as system information, an RAR message, a paging message, or a contention resolution message) only on one sub-band resource of the carrier, a capacity of the information such as the RAR message, the paging message, or the contention resolution message (or the control information for scheduling information such as an RAR message, a paging message, or a contention resolution message) is limited.
For increasing the capacity of the information such as the RAR message, the paging message, or the contention resolution message (or the control information for scheduling information such as an RAR message, a paging message, or a contention resolution message), the base station transmits the information such as the system information, the RAR message, the paging message, or the contention resolution message (or the control information for scheduling information such as system information, an RAR message, a paging message, or a contention resolution message) on all sub-band resources of the carrier. However, consequently, the base station sends much repeated system information (or control information for scheduling system information), a system resource is wasted, and power consumption of the base station is increased.
In addition, in a carrier aggregation scenario, when multiple carriers are configured for a base station, information such as system information, an RAR message, a paging message, or a contention resolution message (or control information for scheduling information such as system information, an RAR message, a paging message, or a contention resolution message) is transmitted only on a primary component carrier. Therefore, a problem of a limited capacity still exists.